Kosher Revolution's Be-All, End-All Chicken Soup

4- to 5-pound stewing chicken

lbs Chicken legs

Celery stalks, medium

Leeks

Onion, medium

Parsnips, medium

Bouquets garnis (2 crushed garlic cloves, 1 bay leaf, 1/2 bunch dill, 1/2 bunch flat-leaf parsley, and 4 peppercorns divided among two squares of cheesecloth, knotted to enclose)

Two 1/2-pound pieces flanken